Buggy code:
public class Mubble { private final char INHERITED = 'i' ; private final char NEW = 'n' ; private final char OVERLOADED = 'l' ; private final char OVERWRITTEN = 'w' ; boolean constructor ; boolean main ; boolean staticMethod ; char flag ; Bubble className ; Pubble packageName ; String methodName ; String group ; String returnType ; String visibility ; String originallyFrom ; ArrayList < String > paraName ; ArrayList < String > paraType ; ArrayList < String > paraMod ; ArrayList < Field > parameters ; String code ; public Mubble ( String methodName ) { } public Mubble ( Mubble m ) { } public boolean isPrivate ( ) { } public void addCode ( String code ) { } public void prependCode ( String ncode ) { } public void addParameter ( Field parameter ) { } public void mangleName ( String name2 ) { } public boolean belongToGroup ( String g ) { } public int rank ( ArrayList < String > type ) { } public String getCode ( ) { } public String findBirthPlace ( ) { } public String getCC ( ) { } public String ccHeader ( ) { StringBuilder s = new StringBuilder ( "" ) ; if ( staticMethod ) { s . append ( returnType ) . append ( "<seq2seq4repair_space>_" ) . append ( getClassName ( ) ) . append ( "::" ) . append ( methodName ) . append ( "(" ) ; for ( int i = 0 ; i < ( paraType . size ( ) ) ; i ++ ) { if ( i != 0 ) { s . append ( ",<seq2seq4repair_space>" ) . append ( ( ( ( paraType . get ( i ) ) + "<seq2seq4repair_space>" ) + ( paraName . get ( i ) ) ) ) ; } else { <START_BUG> s . append ( ( ( paraType . get ( i ) ) + ( paraName . get ( i ) ) ) ) ; <END_BUG> } } s . append ( ")" ) ; } else { if ( ! ( this . isConstructor ( ) ) ) { s . append ( returnType ) ; s . append ( "<seq2seq4repair_space>_" ) . append ( getClassName ( ) ) . append ( "::" ) . append ( methodName ) . append ( "(" ) ; if ( this . isDelete ( ) ) s . append ( "_" ) ; s . append ( getClassName ( ) ) ; if ( this . isDelete ( ) ) s . append ( "*" ) ; s . append ( "<seq2seq4repair_space>__this" ) ; for ( int i = 0 ; i < ( paraType . size ( ) ) ; i ++ ) { s . append ( ",<seq2seq4repair_space>" ) . append ( ( ( ( paraType . get ( i ) ) + "<seq2seq4repair_space>" ) + ( paraName . get ( i ) ) ) ) ; } s . append ( ")" ) ; } else { s . append ( ( ( ( ( "_" + ( className . getName ( ) ) ) + "::_" ) + ( className . getName ( ) ) ) + "(" ) ) ; boolean isFirst = true ; for ( Field f : this . getParameters ( ) ) { if ( ! isFirst ) s . append ( ",<seq2seq4repair_space>" ) ; if ( isFirst ) isFirst = false ; s . append ( ( ( ( f . type ) + "<seq2seq4repair_space>" ) + ( f . name ) ) ) ; } s . append ( "):<seq2seq4repair_space>__vptr(&__vtable)" ) ; } } return s . toString ( ) ; } public String forward ( ) { } public char getFlag ( ) { } public String getClassName ( ) { } public Bubble getBubble ( ) { } public String getGroup ( ) { } public Pubble getPackage ( ) { } public String getPackageName ( ) { } public String getName ( ) { } public String getReturnType ( ) { } public String getVisibility ( ) { } public ArrayList < String > getParameterNames ( ) { } public ArrayList < String > getParameterModifier ( ) { } public ArrayList < String > getParameterTypes ( ) { } public ArrayList < Field > getParameters ( ) { } public boolean isConstructor ( ) { } public boolean isDelete ( ) { } public boolean isMain ( ) { } public boolean isStatic ( ) { } public Mubble setBubble ( Bubble className ) { } public Mubble setConstructor ( boolean constructor ) { } public Mubble setFlag ( char flag ) { } public Mubble setMain ( boolean main ) { } public Mubble setPackage ( Pubble packageName ) { } public Mubble setReturnType ( String returnType ) { } public Mubble setStatic ( boolean staticMethod ) { } public Mubble setVisibility ( String visibility ) { } public Mubble setParameters ( ) { } public Mubble setParameterNames ( ArrayList < String > paraName ) { } public Mubble setParameterTypes ( ArrayList < String > paraType ) { } public String vTable1 ( ) { } public String vTable2 ( ) { } public Mubble copy ( ) { } }

Fix:
s . append ( ( ( ( paraType . get ( i ) ) + "<seq2seq4repair_space>" ) + ( paraName . get ( i ) ) ) ) ;